Before being taken to a judge, these persons under suspicion will have their cheeks swabbed by the cops, who will have been trained for this penetrating forensic assignment at the Police Academy—where I do not expect there will be any accompanying instruction on the Fourth and Fourteenth amendments and the guarantee of "equal protection of the laws."

These DNA markers—which are far more revealing of deeply personal information than mere fingerprints—will then be sent to the state police crime laboratory in Albany to be placed in a huge (and expanding) DNA database.

Bloomberg's contribution to the obsolescence of personal privacy is in ominous harmony with National Intelligence Director Michael McConnell's desire—as reported by Wired magazine—to give "the U.S. government . . . unfettered and warrantless access to U.S. citizens' Google search histories, private e-mails and file transfers, in order to spot the cyberterrorists in our midst."

As the DNA of arrestees is harvested in our ever-expanding surveillance society, New Yorkers should be informed of the dangerous imperfections—to say the least—in our government harvesting such "evidence."

When Governor Eliot Spitzer wanted to expand New York State's DNA collecting to include not just every convicted felon, but also every person convicted of a misdemeanor—a proposal that still wasn't as radical as Bloomberg's suggestion of testing every arrestee—the move failed in the legislature. So far.

But before we were rescued from Big Brother Spitzer, Robert Perry, the New York Civil Liberties Union's legislative director, testified, in dissent, before the New York State Committees on Codes and Correction.

Here are some of Perry's revelations of the privacy minefield into which the clueless Michael Bloomberg would recklessly lead us:

"Even when a DNA sample is of good quality . . . the collection, processing and handling of DNA samples introduces many more opportunities for error. This has led to a rash of DNA testing errors in labs throughout the country due to cross-contamination and mislabeling of samples."

Perry cites the city of Houston's decision to shut down the DNA and serology section of its crime laboratory and—among other grim illustrations—the fact that "an investigation conducted in 2004 by the Seattle Post-Intelligencer documented twenty-three DNA testing errors in serious criminal cases that had been handled by the Washington State Patrol Laboratory."

Perry refers to a 2006 article by William C. Thompson, a professor in the Department of Criminology, Law, and Society at the University of California at Irvine, that documents an alarming and wide-ranging number of errors in the handling and interpretation of DNA evidence.

And, as an inveterate watcher of TV crime dramas with forensic surprises—sometimes deliberately tilting in favor of the prosecution—I particularly noted one of Thompson's observations:

"We often see indications in the laboratory notes themselves [in DNA case files] that the [crime lab] analysts are familiar with the facts of their cases, including information that has nothing to do with genetic testing, and that they are acutely aware of which results will help or hurt the prosecution team. . . . " (emphasis added).

"A DNA analyst in one case wrote: . . . 'Death penalty case. Need to eliminate other individual as a possible suspect.' " (The analyst, in other words, is saying that the district attorney's office already has a suspect, so why screw up the prosecution's case?)

In his zeal to show his intense devotion to national security—as a sometime future president of the United States, if not this time around—Bloomberg is blithely indifferent to the certainty that his enormous expansion of DNA collecting by law enforcement will add to the wide scope of falsely incriminating errors in the DNA analyses.

The Innocence Project, based in New York, has shown many times over that DNA probes can be used to rescue people wrongly convicted of serious felonies from long prison terms and even death row. But when a crime lab, especially if it's overwhelmed, consistently produces less-than-competent work—or is just plain dysfunctional—it will contribute to convicting people whose actual innocence may never be proved.

"New York law does not mandate external blind proficiency testing of DNA laboratories. Such testing is discretionary and contingent," warns Perry.

Also, "[New York] State law fails to recognize that in order to ensure the integrity of DNA laboratories, they must be independent of undue influences by law enforcement and other state agencies. . . . "

And dig this—not only with regard to Bloomberg, but also whether Governor Spitzer will characteristically try again to bull through his expansion of DNA collecting. Said Perry in his testimony:

"[New York] State also permits localities throughout the state to collect and store the DNA of innocent persons, even when these individuals have been excluded as crime suspects. These so-called rogue databases operate outside the law, yet the state has taken no action to close the labs or to require compliance with regulatory procedures or guidelines. No legislation should be advanced regarding the DNA database until all laboratories are in compliance with state and federal laws."

As for Bloomberg's proposal to collect DNA on this city's streets, his criminal-justice coordinator, John Feinblatt, told The New York Times 's Al Baker (January 19) that there's nothing for the innocents among us to worry about: "Very little training [is] needed for police officers to do the swabbing." And at the state police crime lab in Albany, "a huge statewide apparatus" has been handling the ever-increasing DNA caseload for years.

It's safe and simple, he added, to prevent "homicides and rapes and robberies and burglaries . . . the kinds of cases where most commonly you find DNA evidence."

Eventually, there ought to be a statue of this formidable mayor—with a swab in his outstretched hand!